1. Field of the Invention
The present invention relates to a film carrier tape on which electronic devices such as ICs and LSIs are to be mounted, and to a method of manufacturing the film carrier tape. TAB (Tape Automated Bonding), COF (Chip On Film), CSP (Chip Size Package), BGA (Ball Grid Array), xcexc-BGA (xcexc-Ball Grid Array), FC (Flip Chip), and QFP (Quad Flat Package) are exemplified as the film carrier tape.
2. Description of the Related Art
Development of the electronics industry has been accompanied by sharp demand for printed wiring boards for mounting electronic devices thereon, such as ICs (Integrated Circuits) and LSIs (Large-Scale Integrated circuits). Manufacturers have attempted to realize small-size, lightweight, and high-function electronic equipment, which has long been desired. To this end, manufacturers have recently come to employ a film carrier tape, such as a TAB tape, a T-BGA tape, an ASIC tape, or a COF tape. Use of film carrier tapes has become increasing important, especially for manufacturers of personal computers, cellular phones, and other electronic equipment employing a liquid crystal display (LCD) that must have high resolution and flatness, as well as a narrow screen-frame area.
Generally, the above-described film carrier tape is manufactured by forming a plurality of wiring patterns on a continuous length of insulating film having sprocket holes provided along respective longitudinal edges of the insulating film, while the insulating film is continuously conveyed.
Standards of EIAJ (Electronics Industries Association of Japan) stipulate that insulating films come in standard widths of 35 mm, 48 mm, and 70 mm.
These conventional film carrier tapes can be produced less expensively by reducing the size of the wiring pattern and providing a narrower width insulting film. However, the conventional production method cannot cope with all types of film carrier tapes.
Specifically, according to the conventional method, the wiring pattern is formed between a pair of rows of sprocket holesxe2x80x94which are provided along respective longitudinal edges of the insulating film, which rows of sprocket holes are at the outer sides of the insulating film thereofxe2x80x94while the insulating film is conveyed and positioned by use of the sprocket holes. Accordingly, the width of a pattern-forming region in which the wiring pattern is to be formed is restricted by the transverse distance between the rows of sprocket holes; the given width of the pattern-forming region cannot fully satisfy the transverse measurement of a predetermined wiring pattern to be formed. In addition, a limitation is imposed on the degree of downsizing of the wiring pattern.
Therefore, when a product, whose analogue has been manufactured from a 48-mm-width insulating film according to the conventional technology, is instead manufactured from a 35-mm-width insulating film, some wiring patterns fail to be contained within a limited pattern-forming region, by a minute difference.
The present inventors have carried out extensive studies in order to solve the aforementioned problems, and have found that the problems can be overcome by use of a film carrier tape for mounting electronic devices thereon which has a specific configuration. The present invention has been accomplished on the basis of this finding.
Thus, an object of the present invention is to provide a film carrier tape for mounting electronic devices thereon which ensures that a predetermined pattern can be contained within a given pattern-forming region and which lowers cost. Another object of the invention is to provide a method of manufacturing the same.
Accordingly, in a first aspect of the present invention, there is provided a film carrier tape for mounting electronic devices thereon, comprising an insulating film serving as a tape substrate, a wiring pattern formed of a conductor layer provided on a surface of the insulating film, and a pair of rows of sprocket holes provided along respective longitudinal edges of the insulating film, which rows of sprocket holes are at the outer sides of the wiring pattern, wherein the shortest distance between said row of sprocket holes and corresponding edges of said wiring pattern is less than 0.7 mm.
Through employing the film carrier tape according to the first aspect, an increased width of the pattern-forming region can be secured, so as to cover the full transverse measurement of a predetermined wiring pattern, thus lowering product cost.
In a second aspect of the present invention, the insulating film may have a plurality of guide holesxe2x80x94which are smaller than the sprocket holes and are to be used in conveyance of film carrier tape during manufacturing of the film carrier tapexe2x80x94provided in such a manner that the guide holes are disposed adjacent to the corresponding longitudinal edges of the insulating film and transversely outward of the sprocket holes.
Through employing the above construction according to the second aspect, since the guide holes can be reduced in size, a required transverse measurement of the pattern-forming region for a predetermined wiring pattern can be secured.
In a third aspect of the present invention, the sprocket holes may be perforated when the insulating film is conveyed and positioned by use of the guide holes.
Through employing the above construction according to the third aspect, the sprocket holes can be perforated in the insulating film surely at predetermined positions after formation of the wiring pattern is completed.
In a forth aspect of the present invention the sprocket holes may be perforated with reference to a plurality of positioning marks for forming sprocket holes, which marks are formed of the conductor layer by etching.
Through employing the above construction according to the forth aspect, the sprocket holes can be reliably perforated in the insulating film at predetermined positions after formation of the wiring pattern is completed.
In a fifth aspect of the present invention, the insulating film may have one or more device holes arranged longitudinally in the center of a pattern-forming region in which the wiring pattern is provided.
According to the fifth aspect, employing the above construction, enables manufacture of various types of film carrier tapes for mounting electronic devices thereon with precise measurements.
According to a sixth aspect of the present invention, there is provided a method of manufacturing a film carrier tape for mounting electronic devices thereon which includes an insulating film, serving as a tape substrate, a wiring pattern formed of a conductor layer provided on a surface of the insulating film, and a pair rows of sprocket holes provided along respective longitudinal edges of the insulating film, which rows of sprocket holes are at the outer sides of the wiring pattern, the method comprising perforating, prior to formation of the wiring pattern, a plurality of guide holes, which are smaller than the sprocket holes and are to be used in conveyance of film carrier tape during manufacturing of the film carrier tape, in the insulating film along the longitudinal edges thereof in such a manner that the perforated guide holes are disposed adjacent to the corresponding longitudinal edges of the insulating film and transversely outward of the sprocket holes; forming the wiring pattern formed of a conductor layer on the insulating film as conveyed and positioned by use of the guide holes, by patterning the conductor layer on the positioned insulating film; and, subsequent to the patterning, perforating the sprocket holes in the insulating film as conveyed and positioned by use of the guide holes.
Through employing the above method according to the sixth aspect, after a predetermined wiring pattern is reliably formed in a widened pattern-forming region, the sprocket holes can be reliably perforated in respective predetermined positions of the insulating film, thus lowering product cost.
In a seventh aspect of the present invention perforation of the guide holes may be carried out by punching through the insulating film and the conductor layer provided on the entire surface of the insulating film.
Through employing the above method according to the seventh aspect, the insulating film can be conveyed and positioned by use of the guide holes.
In a eighth aspect of the present invention, after perforation of the guide holes, the conductor layer may be formed between the guide holes along the respective longitudinal edges of the insulating film, after which forming of the conductor layer forming of the wiring pattern is carried out.
Through employing the above method according to the eighth aspect, the predetermined wiring pattern can be fully formed by increasing the width of a pattern-forming region.
In a ninth aspect of the present invention, the shortest distance between the sprocket holes and corresponding edges of the wiring pattern may be less than 0.7 mm.
Through employing the above method according to the ninth aspect, the predetermined wiring pattern can be fully formed by increasing the width of a pattern-forming region.
In a tenth aspect of the present invention, along with the guide holes, one or more device holes may be perforated by punching through the insulating film.
According to the tenth aspect, employing the above method enables manufacture of various types of film carrier tapes for mounting electronic devices thereon, with precise measurements.
In a eleventh aspect of the present invention, along with the sprocket holes, one or more device holes may be perforated by punching through the insulating film.
According to the eleventh aspect of the present invention, employing the above method enables manufacture of various types of film carrier tapes for mounting electronic devices thereon, with precise measurements.
According to a twelfth aspect of the present invention, there is provided a method of manufacturing a film carrier tape for mounting electronic devices thereon which includes an insulating film, serving as a tape substrate, a wiring pattern which is formed of a conductor layer provided on a surface of the insulating film and on which electronic devices are to be mounted, and a pair of rows of sprocket holes provided along respective longitudinal edges of the insulating film, which rows of sprocket holes are at the outer sides of the wiring pattern, the method comprising forming the wiring pattern by patterning the conductor layer when the insulating film is conveyed and positioned while feed rollers pinch portions thereof that are adjacent to the respective longitudinal edges of the wiring pattern; forming a plurality of positioning marks at each of the sprocket hole positions of the conductor layer; and subsequently perforating the sprocket holes by punching the positioning marks along with the insulating film.
Through employing the above method according to the twelfth aspect, after a predetermined wiring pattern is reliably formed in a widened pattern-forming region, the sprocket holes can be reliably perforated at respective predetermined positions of the insulating film, thus lowering product cost.
In a thirteenth aspect of the present invention, the shortest distance between the sprocket holes and corresponding edges of the wiring pattern may be less than 0.7 mm.
Through employing the above method according to the thirteenth aspect, the predetermined wiring pattern can be fully formed by increasing the width of a pattern-forming region.
In a fourteenth aspect of the present invention, along with the sprocket holes, one or more device holes may be perforated by punching the insulating film.
According to the fourteenth aspect, employing the above method enables manufacture of various types of film carrier tapes for mounting electronic devices thereon, with precise measurements.